Under the LT2 Rule, systems monitored their water sources to determine treatment requirements.  This monitoring included an initial two years of monthly sampling for Cryptosporidium. To reduce monitoring costs, small filtered water systems (serving fewer than 10,000) first monitored for E. coli—a bacterium which is less expensive to analyze than Cryptosporidium—and then monitored for Cryptosporidium if their E. coli results exceeded specified concentration levels.

To understand how EPA prepared the data for analysis, please see the pdf document at the bottom of this page.

• Cryptosporidium “cleaned up” data from monitoring under the LT2 Rule (CSV)(1 pg, 7 MB) This file contains a “cleaned up” version of the Cryptosporidium data collected under Round 1 source water monitoring as required by the LT2 Rule. A brief description of the data “clean up” process is provided in the document “Preparation of Round 1 LT2 monitoring data for EPA analyses” (see link at the bottom of this page). This “cleaned up” dataset also includes a dictionary describing the data fields.

• E. coli “cleaned up” data from monitoring under the LT2 Rule (CSV)(1 pg, 7 MB) This file contains a “cleaned up” version of the E. coli and turbidity monitoring data collected under Round 1 source water monitoring as required by the LT2 Rule.  A brief description of the data “clean up” process is provided in the document “Preparation of Round 1 LT2 monitoring data for EPA analyses" (see link at the bottom of this page). This “cleaned up” dataset also includes a dictionary describing the data fields.

• Cryptosporidium raw data from monitoring under the LT2 Rule (CSV) (1 pg, 14 MB) This file contains Cryptosporidium data collected under the Round 1 source water monitoring as required by the LT2 Rule. The data are used by utilities to determine whether additional treatment for Cryptosporidium is needed. A data dictionary is included.

• E. coli raw data from monitoring under the LT2 Rule (CSV) (1 pg, 18 MB) This file contains E. coli and turbidity data collected under the Round 1 source water monitoring as required by the LT2 Rule. The E. coli data are used by small filtered water systems as a screen for Cryptosporidium to determine whether additional treatment and/or monitoring for Cryptosporidium is needed. A data dictionary is included.

• Preparation of Round 1 LT2 Rule monitoring Data for EPA analyses (PDF)(3 pp, 132 K, Nov 10, 2012)
  This document describes the quality assurance (QA) and quality control (QC) steps that were taken to assess the LT2 Rule Round 1 Cryptosporidium and E. coli source water monitoring raw data. The document also describes potential data quality concerns.